1. Field of the Invention
The present invention relates to a recording electrode used in recording apparatuses such as a facsimile machine or a printer.
2. Description of the Related Art
There have been known recording apparatuses of the type in which a recording electrode is used. One type of the recording electrode is made up of an electrically insulating base film formed with apertures therein, and a control electrode formed on the surface of the base film to surround the apertures. A high molecular compound, such as polyester or polyimide, is used for the base film. The apertures are formed by excimer laser. The control electrode is formed from metals such as copper or aluminum.
The recording apparatus using such a recording electrode includes a toner charging means for charging toner particles, a toner-bearing drum for bearing and conveying the charged toner particles, a control voltage applying circuit for applying a voltage to the control electrode of the recording electrode, and a back electrode disposed to confront the toner-bearing drum with a small spacing formed therebetween. The recording electrode is held so that the rear surface thereof faces the toner-bearing drum and the portion around the apertures is in contact with the toner-bearing drum. Frictional resistive force is imparted on the toner particles deposited on the surface of the toner-bearing drum in the direction opposite the toner conveying direction. Shearing force resulting from the frictional resistive force and attraction force by the toner-bearing drum is imparted on the toner particles. The shearing force quivers the toner particles on the toner-bearing drum. The frictional resistive force is proportional to the contacting pressure between the recording electrode and the toner-bearing drum.
The quivering toner particles are free from attraction force for attracting the toner particles to the toner-bearing drum, such as image force or Van der Waals force. Coulomb force is generated by the electric field that is developed inside the apertures by the voltage applied to the control electrode. This Coulomb force is imparted on the toner particles free from the attraction force. The Coulomb force controls the passage of the charged toner particles through the apertures. The toner particles which have passed through the apertures are attracted by the back electrode and thus captured by a recording medium introduced into the spacing between the back electrode and the toner-bearing drum. In this manner, an image is formed on the recording medium in accordance with the voltage applied to the control electrode.
A problem with the above-described recording apparatus is that the density of an image formed on the recording medium is locally uneven.